that he had the right agenda to turn the nation around. and after a roller coaster season, he got them. mitt romney may have started off at the front runner, but to win the republican nomination, he had to fend off some feisty challengers. >> he's the worst republican in the country to put up against president obama. >> reporter: and overcome some self-inflicted wounds. after 50 primary contests, romney clenched the nomination and it was on to the general election. >> it will be a choice between -- >> two very different paths. >> reporter: their battle focused on the economy. >> we can't afford another four years like the last four years. >> we need more tax cuts for working americans. >> reporter: early on, two key moments changed the subject that helped the president. >> i think same-sex couples should be able to get married. >> the supreme court has upheld that every american buy health insurance. >> reporter: in june, president obama announced a new policy that would allow at least 800,000 young immigrants facing deportation to stay in